gatsby-node.js

const path = require('path')
const _ = require('lodash')
const moment = require('moment')
const siteConfig = require('./_site-config')
const { createFilePath } = require(`gatsby-source-filesystem`)

const postNodes = []

// Fetching remote data https://github.com/gatsbyjs/gatsby/blob/5a08b7640c2db2c65696be56d81afee83b2ca9ec/examples/using-unstructured-data/gatsby-node.js
// Big example https://github.com/gatsbyjs/gatsby/blob/master/www/gatsby-node.js

function addSiblingNodes(createNodeField) {
  postNodes.sort(
    ({ frontmatter: { date: date1 } }, { frontmatter: { date: date2 } }) => {
      const dateA = moment(date1, siteConfig.dateFromFormat)
      const dateB = moment(date2, siteConfig.dateFromFormat)

      if (dateA.isBefore(dateB)) return 1

      if (dateB.isBefore(dateA)) return -1

      return 0
    }
  )
  for (let i = 0; i < postNodes.length; i += 1) {
    const nextID = i + 1 < postNodes.length ? i + 1 : 0
    const prevID = i - 1 > 0 ? i - 1 : postNodes.length - 1
    const currNode = postNodes[i]
    const nextNode = postNodes[nextID]
    const prevNode = postNodes[prevID]
    createNodeField({
      node: currNode,
      name: 'nextTitle',
      value: nextNode.frontmatter.title
    })
    createNodeField({
      node: currNode,
      name: 'nextSlug',
      value: nextNode.fields.slug
    })
    createNodeField({
      node: currNode,
      name: 'prevTitle',
      value: prevNode.frontmatter.title
    })
    createNodeField({
      node: currNode,
      name: 'prevSlug',
      value: prevNode.fields.slug
    })
  }
}

exports.onCreateNode = ({ node, actions, getNode }) => {
  const { createNodeField } = actions
  let slug

  if (node.internal.type === `MarkdownRemark`) {
    const fileNode = getNode(node.parent)
    console.log(`\n`, fileNode.relativePath)
    const test = createFilePath({ node, getNode, basePath: `pages` })
    console.log('test', test)
  }
  if (node.internal.type === 'MarkdownRemark') {
    const fileNode = getNode(node.parent)
    const parsedFilePath = path.parse(fileNode.relativePath)
    if (
      Object.prototype.hasOwnProperty.call(node, 'frontmatter') &&
      Object.prototype.hasOwnProperty.call(node.frontmatter, 'title')
    ) {
      console.log('Set title as slug', node.frontmatter.title)
      slug = `/${_.kebabCase(node.frontmatter.title)}`
    } else if (parsedFilePath.name !== 'index' && parsedFilePath.dir !== '') {
      slug = `/${parsedFilePath.dir}/${parsedFilePath.name}/`
    } else if (parsedFilePath.dir === '') {
      slug = `/${parsedFilePath.name}/`
    } else {
      slug = `/${parsedFilePath.dir}/`
    }

    if (Object.prototype.hasOwnProperty.call(node, 'frontmatter')) {
      if (Object.prototype.hasOwnProperty.call(node.frontmatter, 'slug')) {
        slug = `/${_.kebabCase(node.frontmatter.slug)}`
      }

      if (Object.prototype.hasOwnProperty.call(node.frontmatter, 'date')) {
        const date = moment(node.frontmatter.date, siteConfig.dateFromFormat)
        if (!date.isValid) { console.warn(`WARNING: Invalid date.`, node.frontmatter) }

        createNodeField({
          node,
          name: 'date',
          value: date.toISOString()
        })
      }
    }
    createNodeField({ node, name: 'slug', value: slug })
    postNodes.push(node)
  }
}

exports.setFieldsOnGraphQLNodeType = ({ type, actions }) => {
  const { name } = type
  const { createNodeField } = actions
  if (name === 'MarkdownRemark') {
    addSiblingNodes(createNodeField)
  }
}

exports.createPages = ({ graphql, actions }) => {
  const { createPage } = actions

  return new Promise((resolve, reject) => {
    const postPage = path.resolve('src/templates/Post.js')
    const tagPage = path.resolve('src/templates/Tag.js')
    const categoryPage = path.resolve('src/templates/Category.js')
    resolve(
      graphql(
        `
          {
            allMarkdownRemark {
              edges {
                node {
                  frontmatter {
                    tags
                    category
                  }
                  fields {
                    slug
                  }
                }
              }
            }
          }
        `
      ).then(result => {
        if (result.errors) {
          /* eslint no-console: "off" */
          console.log(result.errors)
          reject(result.errors)
        }

        const tagSet = new Set()
        const categorySet = new Set()
        result.data.allMarkdownRemark.edges.forEach(edge => {
          if (edge.node.frontmatter.tags) {
            edge.node.frontmatter.tags.forEach(tag => {
              tagSet.add(tag)
            })
          }

          if (edge.node.frontmatter.category) {
            categorySet.add(edge.node.frontmatter.category)
          }

          createPage({
            path: edge.node.fields.slug,
            component: postPage,
            context: {
              slug: edge.node.fields.slug
            }
          })
        })

        const tagList = Array.from(tagSet)
        tagList.forEach(tag => {
          createPage({
            path: `/tags/${_.kebabCase(tag)}/`,
            component: tagPage,
            context: {
              tag
            }
          })
        })

        const categoryList = Array.from(categorySet)
        categoryList.forEach(category => {
          createPage({
            path: `/categories/${_.kebabCase(category)}/`,
            component: categoryPage,
            context: {
              category
            }
          })
        })
      })
    )
  })
}

/* Shrink CSS class names in prod */
const cssLoaderRe = /\/css-loader\//;
const targetFile = '.css';

const processRule = rule => {
  // console.log('rule', rule)
  if (rule.oneOf) {
    return {
      ...rule,
      oneOf: rule.oneOf.map(processRule),
    };
  }

  if (!rule.test.test(targetFile)) {
    return rule;
  }

  if (Array.isArray(rule.use)) {
    return {
      ...rule,
      use: rule.use.map(use => {
        if (!cssLoaderRe.test(use.loader)) {
          return use;
        }
        // console.log('use', use)
        // Adjust css-loader options
        return {
          ...use,
          options: {
            ...use.options,
            localIdentName:
              process.env.NODE_ENV === 'production'
                ? '[hash:base64:5]'
                : '[name]_[local]_[hash:base64:4]',
          },
        };
      }),
    };
  }

  return rule;
};

exports.onCreateWebpackConfig = ({ getConfig, actions }) => {
  const config = getConfig();

  const newConfig = {
    ...config,
    module: {
      ...config.module,
      rules: config.module.rules.map(processRule),
    },
  };
  actions.replaceWebpackConfig(newConfig);
};